Genetic variation in susceptibility of Atlantic salmon to furunculosis

The purpose of this experiment was to study the magnitude of genetic variation in mortality due to experimental furunculosis; furunculosis is the most serious salmon disease in Norway at present. Fifty fulisib- and 25 paternal halfsib groups of Atlantic salmon, in total 5000 fish, were infected with Aeromonas salmonicida ssp. salmonicida at Vikan AkvaVet, Namsos. Infection was by means of cohabitation, and all fish were marked and kept in the same tank during the experiment. The death rate averaged 68% with large variation between family groups. Heritability of mortality was high, h 2 = 0.48 ± 0.17 for the sire component and h 2 = 0.32 ± 0.10 for the dam component estimates. It is concluded that resistance to furunculosis can be effectively improved by selective breeding.